So as you can see in these pictures, I'm doing this whole build in my crowded 1 car garage.
My township doesn't allow major car repair in the driveway.
So here's the firewall after I cleaned up the support that attaches to the support on the new floor.
By the way, all this work is done with a grinder with cut-off wheels, grinding wheels and flapper sanding wheels.
I also use a saws-all and regular hand tools.
I don't have air tools (yet).
The back wall had some rust on it. I got it all out, but it was almost bad enough to need a new piece of metal between the new cab corners.